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CVE-2023-26552 Siemens CVE debrief

CVE-2023-26552 is a medium-severity out-of-bounds write vulnerability in the mstolfp function within libntp/mstolfp.c in NTP 4.2.8p15. The flaw occurs when adding a decimal point, potentially allowing an adversary to attack a client ntpq process. Notably, the ntpd daemon itself cannot be attacked via this vulnerability. The issue affects Siemens SITOP UPS1600 industrial power supply units with Ethernet/PROFINET interfaces, specifically models 6EP4134-3AB00-2AY0 (10A), 6EP4136-3AB00-2AY0 (20A), 6EP4137-3AB00-2AY0 (40A), and 6EP4136-3AC00-2AY0 (EX 20A). Published on June 11, 2024, this CVE was disclosed through coordinated government-industry advisory channels. Siemens has released firmware version 2.5.4 or later to remediate this vulnerability in affected products.

Vendor
Siemens
Product
SITOP UPS1600 10 A Ethernet/ PROFINET (6EP4134-3AB00-2AY0)
CVSS
MEDIUM 5.6
CISA KEV
Not listed in stored evidence
Original CVE published
2024-06-11
Original CVE updated
2024-06-11
Advisory published
2024-06-11
Advisory updated
2024-06-11

Who should care

Industrial operations teams deploying Siemens SITOP UPS1600 power supplies in manufacturing, energy, or critical infrastructure environments; OT security practitioners managing NTP client configurations; and asset owners requiring coordinated vulnerability response for PROFINET-connected industrial devices.

Technical summary

The mstolfp function in NTP 4.2.8p15's libntp/mstolfp.c contains an out-of-bounds write triggered during decimal point insertion. This client-side vulnerability in ntpq—NTP's query utility—permits memory corruption but does not extend to the ntpd server daemon. Attack complexity is high (CVSS:3.1/AC:H), limiting practical exploitation. Siemens has patched affected SITOP UPS1600 firmware; the fix is available through standard support channels.

Defensive priority

medium

Recommended defensive actions

  • Apply Siemens firmware update V2.5.4 or later to all affected SITOP UPS1600 models
  • Verify current firmware version through Siemens Industry Online Support portal
  • Review network segmentation for industrial control systems per CISA ICS recommended practices
  • Monitor for anomalous ntpq client activity on systems managing affected UPS units
  • Consult Siemens SSA-238730 security advisory for detailed remediation guidance

Evidence notes

Vulnerability description and affected product details sourced from CISA CSAF advisory ICSA-24-165-05 and Siemens product security advisory SSA-238730. CVSS 3.1 vector confirms network attack vector with high attack complexity, requiring no privileges or user interaction.

Sources and references

Verified primary and authoritative sources

  • CVE-2023-26552 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2023-26552

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2023-26552 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2023-26552

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2024/icsa-24-165-05.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-238730.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-238730.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/pdf/ssa-238730.pdf

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/txt/ssa-238730.txt

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-24-165-05

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/uscert/ics/alerts/ICS-ALERT-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.